1. Field of the Invention
This invention relates to a fastening assembly comprising a bolt and a keeper with which the bolt is engageable, for fastening doors or windows.
2. Description of Prior Art
Fastening assemblies each comprising a bolt and a keeper are well known for fastening doors or windows, and there are many different types of such fastening assembly. What such types have in common is a bolt carried by a Support means and movable relative thereto between an extended position in which the bolt is able to engage with the keeper and a retracted position in which it is not able to engage the keeper. Usually, support means for the bolt is mounted on an openable panel of the door or window and the keeper on the fixed frame relative to which the panel is openable. In its simplest form, the bolt is able to be directly manually, moved between its extended and retracted positions, but in more complex forms there are many different types of mechanism by which the bolt is movable. The bolt may form part of a lock, i.e. be movable between its extended and retracted positions by use directly or indirectly of a key.
A bolt for a pivotally openable window or door is usually provided at an edge of the window or door remote from the hinge or hinges by which the window or door is mounted relative to its fixed frame, the bolt being movable in a direction parallel or substantially parallel to the general plane of the window or door, to protrude beyond such edge of the window or door when it is in its extended position, thereby to be engageable with the keeper which is provided on or in the fixed frame. In some cases, however, it might be possible by application of force to effect relative movement between the window or door and fixed frame in the direction of retraction of the bolt, thereby to disengage the bolt from the keeper and permit the window or door to be opened without extraction of the bolt. There are fastening assemblies which aim to defeat the opening of a fastened window or door in this manner, but with the drawback of greater complexity, e.g. by requiring a bolt mounted to its support means in a manner enabling it to be moved in an arcuate path of movement.
Various forms of fastening assembly offering improved security are disclosed for example in the following references:
GB-2134960 discloses a locking device with a latch bolt engageable by a retaining element, in order to prevent the bolt from being forced back from its locking position. GB-1505455 discloses a sliding bolt fastening device for a vehicle panel or tailboard, with a toggle mechanism arranged to provide a self-tightening effect. GB-1422321 discloses a bolt which is lockable against axial releasing movement from its keep, by means of a plug which extends into the bolt and operates a detent mechanism. GB-1046541 discloses a lock whose bolt also includes an axial slider. After the bolt head has passed through a slot in the striker, the slider enters the slot to prevent withdrawal of the bolt from the slot. U.S. Pat. No. 4,512,597 discloses a lock whose bolt has auxiliary locking elements movable outwardly by a central plunger. U.S. Pat. No. 4,312,527 discloses a locking mechanism which utilises spaced plates with T-shaped tongues, between which bolt members are movable.